US 5,946,012 A · Reliable high performance drop generator for an inkjet printhead

Abstract

An inkjet drop ejection system comprises a combination of printhead components and ink, mutually tuned to maximize operating characteristics of the printhead and print quality and dry time of the ink. Use of a short shelf (distance from ink source to ink firing element), on the order of 55 microns, provides a very high speed refill. However, it is a characteristic of high speed refill that it has a tendency for being over-damped. To provide the requisite damping, the ink should have a viscosity greater than about 2 cp. In this way, the ink and architecture work together to provide a tuned system that enables stable operation at high frequencies. One advantage of the combination of a pigment and a dispersant in the ink is the resultant higher viscosity provided. The high speed would be of little value if the ink did not have a fast enough rate of drying. This is accomplished by the addition of alcohols or alcohol(s) and surfactant(s) to the ink. Fast dry times are achieved with a combination of alcohols, such as iso-propyl alcohol with a 4 or 5 carbon alcohol or with iso-propyl alcohol plus surfactant(s). One preferred embodiment of a short shelf (90 to 130 microns), ink viscosity of about 3 cp, and surface tension of about 54 provides a high speed drop generator capable of operating at about 12 KHz. Reducing the shelf length to about 55 microns, in combination with rotating the substrate at an angle to the scan direction, permits maximum drop generator operation as high as about 20 KHz. As a consequence of employing pigment-based inks, high optical densities are realized, along with excellent permanence (no fade and better waterfastness), and good stability. The combination of preferred ink and pen architecture provides good drop generator stability.

An inkjet drop ejection system comprising:

(a) a substantially rectangular substrate having a top surface and an opposing bottom surface, and having a first outer edge along a periphery of said substrate and a second outer edge along said opposite periphery of said substrate;
(b) a nozzle member having a plurality of ink orifices formed therein, said nozzle member being positioned to overlie said top surface of said substrate;
(c) first and second pluralities of ink ejection elements formed on said top surface of said substrate, each of said ink ejection elements comprising a firing element in a vaporization chamber and being located approximate to an associated one of said orifices for causing a portion of ink to be expelled from said associated orifice as said inkjet drop ejection system is moved along a scan direction, said first plurality of ink ejection elements arranged in a first array along said first outer edge and said second plurality of ink ejection elements arranged in a second array along said second outer edge, each said vaporization chamber and associated orifice being offset from adjacent vaporization chambers and orifices along a direction perpendicular to said scan direction;
(d) an ink reservoir for holding a quantity of ink;
(e) a fluid channel, communicating with said reservoir, leading to each of said orifices and said ink ejection elements, said fluid channel allowing ink to flow from said ink reservoir, around said first outer edge of said substrate and to said top edge of said substrate so as to be proximate to said orifices and said ink ejection elements;
(f) a separate inlet passage defined by a barrier layer for each vaporization chamber connecting said fluid channel with said vaporization chamber for allowing high frequency refill of said vaporization chamber;
(g) a group of said firing elements in adjacent relationship forming a primitive in which only one firing element in said primitive is activated at a time by a combination of a primitive select signal and a firing element address signal, said address signals associated with each firing element in a primitive being sequentially generated in time in a fixed sequence, the timing of the firing of offset firing elements in a said primitive by said sequence address signals being such that later-occurring address signals in said fixed sequence control the firing of offset firing elements that are located downstream from other firing elements in each of said first array and said second array with respect to said scan direction, the combination of the firing of one firing element in a primitive at a time and the firing of offset firing elements by later-occurring address signals in said fixed sequence thereby reducing cross-talk between vaporization chambers;
(h) circuit means for transmitting firing signals to said ink firing elements at a maximum frequency greater than 9 KHz;
and
(i) said inkjet drop ejection system forming a part of a color set comprising at least one ink, said ink comprising at least one colorant in an aqueous vehicle.

7 more elements

Facts

Application

09/090,968Filed 4 Jun 1998 · continuation

Priority

2 Apr 1992

Granted

31 Aug 1999

Term ends

Not estimatedThe source records don’t support an estimate.

Classification22 codes

B41J 2/1643
Thin film formation: thin film formation by plating
B41J 2/04511
Control methods or devices therefor, e.g. driver circuits, control circuits: for electrostatic discharge protection
B41J 2/04541
Control methods or devices therefor, e.g. driver circuits, control circuits: specific driving circuit
B41J 2/04543
Control methods or devices therefor, e.g. driver circuits, control circuits: block driving

Family

Serial862,086Parent of this continuation · filed 2 Apr 1992

Serial179,866Parent of this continuation-in-part · filed 11 Jan 1994

Serial319,896Parent of this continuation-in-part · filed 6 Oct 1994

Serial608,376Parent of this continuation · filed 28 Feb 1996

US 5,648,805 AParent of this continuation-in-part

US 5,625,396 AParent of this continuation-in-part

US 5,278,584 AParent of this continuation

US 5,946,012 AThis patent

From the US filing history. Foreign family members aren’t listed.

Reliable high performance drop generator for an inkjet printhead

Life of this patent

Reliable high performance drop generator for an inkjet printhead

Life of this patent

Abstract

Claims44